The present invention relates to a magnetic disk drive for recording and reproducing information on a flexible disk housed in a case of a magnetic disk. More specifically, the present invention relates to an improvement of impact measures therefor.
Magnetic disk drives of the type described is some type of a device on which a magnetic disk can be mounted and held by a magnetic disk table for the purpose of recording and reproducing information. The magnetic disk table is for rotation driving the magnetic disk while holding it. A magnetic head is used to record and reproduce information on the magnetic disk. The magnetic disk drives also include a magnetic disk mounting and ejection assembly for use in ejecting a magnetic disk out of the magnetic disk drive after recording or reproduction of information.
FIG. 1 is an exploded perspective view of a typical magnetic disk drive in particular with a magnetic disk mounting and ejection assembly being illustrated separately. In FIG. 1, the magnetic disk drive comprises a chassis 11 formed by pressing a sheet metal, an eject plate 12, and a disk holder 13.
The chassis 11 has a main base section 11-1, opposing side walls 11-2 and 11-3, a back end wall 11-4, two support claws 11-5 and different two support claws 11-6. The side walls 11-2 and 11-3 extend upward at right angles from both side edges of the plate-like main base section 11-1. Likewise, the back end wall 11-4 extends upward at right angles from the rear edge of the main base section 11-1. Each of the support claws 11-5 and 11-6 is formed by means of cutting and raising a portion of the main base section 11-1. The support claws 11-5 and 11-6 have shoulder portions 11-5a and 11-6a, respectively. Each of the shoulder portions 11-5a and 11-6a is a notch formed in the respective support claws.
A magnetic disk table 14 and a carriage mechanism 15 are mounted on the main base section 11-1 in the direction along the side walls of the chassis 11. The magnetic disk table 14 is for rotation driving a magnetic disk while holding it. The carriage mechanism 15 is for use in driving a pair of magnetic heads in the direction of a track in the magnetic disk. More specifically, an upper magnetic head and a lower magnetic head are driven in the track direction on a top surface and a back (under) surface, respectively, of the magnetic disk. A stepping motor 16 is mounted on the back end wall 11-4 of the chassis 11. The stepping motor 16 has a rotation shaft 16-1 with a helical thread therein and is arranged so that the rotation shaft 16-1 extends in the direction along the side walls of the chassis 11. The magnetic disk table 14 is directly connected to and rotation driven by a rotor assembly of a magnetic disk driving motor disposed beneath the chassis 11.
The carriage mechanism 15 has a carriage base body at a rear portion thereof, as described more in detail below. The carriage mechanism 15 is slidably supported by a guide shaft 15-2 that is fixed to the main base section 11-1 at the carriage base body. A carriage arm 15-1 is provided on the carriage base body. The carriage arm 15-1 has a pin at the tip thereof. The pin engages with the helical thread formed in the rotation shaft 16-1. In response to rotation of the stepping motor 16, the carriage arm 15-1 cooperates with the rotation of the stepping motor 16 and reciprocates back and forth. This moves the carriage arm 15-1 linearly in the direction along the side walls of the chassis 11, that is, in the radial direction of the magnetic disk. The carriage mechanism 15 has a lower carriage 15-4 and an upper carriage 15-5. The lower carriage 15-4 carries a magnetic head 15-3 for the back surface of the magnetic disk. The upper carriage 15-5 carries a magnetic head (not shown) for the top surface of the magnetic disk. The upper carriage 15-5 is rotatable about the edge of the carriage base body. The upper carriage 15-1 rotates upward when a magnetic disk is inserted into the carriage mechanism 15 and then rotates downward when the magnetic disk is completely mounted in the disk drive. The upper magnetic head thus approaches the top surface of the magnetic disk.
The eject plate 12 comprises a main plate section 12-1, a side plates 12-2 and 12-3 and a front end projection 12-4. The main plate section 12-1 has a generally U shape. The side plates 12-2 and 12-3 extend vertically from both side edges of the main plate section 12-1. The front end projection 12-4 is for mounting an eject button thereon and extends forward from the front edge of the main plate section 12-1. Two notches 12-5 and two holes 12-6 are formed in the main plate section 12-1 at the position corresponding to the support claws 11-5 and 11-6, respectively, of the chassis 11. Guide grooves 12-7 are formed in the side plates 12-3 and 12-4, two for each side plate. The guide groove 12-7 includes a horizontal portion and a tilt portion.
The eject plate 12 is assembled with the chassis 11 with the support claws 11-5 and 11-6 passed through the notches 12-5 and the holes 12-6, respectively. When being assembled, the configuration of the notches 12-5 and the holes 12-6 of the main plate section 12-1 are supported by the shoulders 11-5a and 11-6a of the support claws 11-5 and 11-6, respectively. Thus the eject plate 12 is slidable back and forth relative to the chassis 11. The eject plate 12 is allowed only slight or no movement in the up and down direction and the right and left directions. Though depending on the actual configurations, the notches 12-5 and the holes 12-6, as well as the support claws 11-5 and 11-6 are limitations to such movement.
As described above, the main plate section 12-1 has a generally U shape. Therefore, the eject plate 12 is slidable without interrupting operation of the magnetic disk table 14 and the carriage mechanism 15.
The disk holder 13 has a main base section 13-1, opposing side walls 13-2 and 13-3, and four projecting pins 13-4. The main base section 13-1 has a notch portion not to cause contact with the upper magnetic head in the carriage mechanism 15. The side walls 13-2 and 13-3 extend downward at right angles from both side edges of the main base section 13-1. The free end of the side walls 13-2 and 13-3 is bent inward to hold the magnetic disk. The projecting pins 13-4 are projected outward from the side walls 13-2 and 13-3 at the position corresponding to the guide grooves 12-7 in the eject plate 12. The disk holder 13 is assembled with the eject plate 12 with the projecting pins 13-4 passed through the guide grooves 12-7.
With the above-mentioned structure the disk holder 13 is slidable upward and downward. The disk holder 13 is allowed only slight or no movement in the back and forth direction and the right and left directions. More specifically, the disk holder 13 is slidable upward and downward in cooperation with the back-and-forth movement of the eject plate 12, depending on the shape of the guide grooves 12-7 formed in the eject plate 12. A tension spring (not shown) is provided between the eject plate 12 and the disk holder 13. The tension spring pulls the eject plate 12 towards the front portion of the chassis 11. The eject plate 12 is locked with a locking member (not shown) at a rear portion of the chassis 11 against the pulling force of the tension spring. In addition, there is an eject member (not shown) provided to apply force, in cooperation with the locking member, to the magnetic disk in the direction to eject it out of the assembly. An eject button 12-8 is mounted on the front end projection 12-4 to allow an operator to eject the magnetic disk.
Next, operation of mounting and ejecting a magnetic disk with the disk holder having the above-mentioned structure is described. In the absence of the magnetic disk, the eject plate 12 is located backward with being locked by the locking member. The tension spring is expanded. In this event, the projection pins 13-4 engage with the horizontal portions of the corresponding guide grooves 12-7. The disk holder is located at an upper portion.
When the magnetic disk is inserted into a slit in the front face of the disk holder 13 located at an upper portion, the locking mechanism is disengaged. The eject plate 12 is pulled by the expanded tension spring and moves forward. The projecting pins 13-4 move downward along the moving guide grooves 12-7. This lowers the disk holder 13 and complete disk mounting operation. The magnetic disk is now ready to be accessed to record and/or reproduce information.
In this state, the eject plate 12 moves backward and is locked again by the locking member when the eject button 12-8 is depressed. The tension spring is kept expanded. Then the projecting pin 13-4 moves upward along the moving guide grooves 12-7. The disk holder 13 thus located upward. The eject member acts on the magnetic disk to eject it out of the assembly in cooperation with the locking member.
The magnetic disk drives of the type described are built in portable electronic devices such as a portable personal computer and a word processor. Such electronic devices often receive vibration and shock particularly when a user picks up it or brings it with him or her to go somewhere. The vibration acts on the built-in magnetic disk drive as well. The vibration or impact may act in the up and down direction of the magnetic disk drive, that is, the vertical direction relative to the chassis 11 with no magnetic disk mounted on the magnetic disk drive. If this happens, the following problems occur. The impact may displace the disk holder 13 downward. The impact may also rotate the upper carriage 15-5 downward to the extent that the magnetic head collides with the magnetic head on the back side, damaging or breaking the magnetic head.
Referring to FIGS. 2 and 3, a magnetic disk drive is described that comprises means to solve the above-mentioned problems. In FIG. 2, a lock plate 17 is rotatably mounted on the disk holder 13 in parallel with the major surface thereof. The lock plate 17 is rotatable about a support shaft 13-5 provided on the major surface of the disk holder 13. The lock plate 17 comprises a locking piece 17-1 and an engaging piece 17-2. The locking piece 17-1 is at a lock position just beneath the upper carriage 15-5 with no magnetic disk mounted on the magnetic disk drive to interfere downward movement of the upper carriage 15-5. The engaging piece 17-2 engages with a front end of the magnetic disk when it is mounted on the magnetic disk drive. The engaging piece 17-2 then rotates the entire lock plate 17. The engaging piece 17-2 extends downward from the major surface of the lock plate 17.
As shown in FIG. 3, the lock plate 17 rotates about the support shaft 13-5 when the front end of a magnetic disk 100 engages with the engaging piece 17-2. The engaging piece 17-2 moves out of the position just beneath the upper carriage 15-5 and releases the lock. A spring member 17-5 is provided between the lock plate 17 and the disk holder 13 to connect them. The spring member 17-5 is for automatically returning the engaging piece 17-2 to the above-mentioned lock position when the magnetic disk is removed out of the disk drive. A lock piece 13-6 is provided at the front end of the disk holder 13 to restrict at the locking position in FIG. 2 the rotation of the lock plate 17 by the spring member 17-5.
With this lock plate 17, the upper carriage 15-5 does not rotate even if the magnetic disk drive is suffered from impact or vibration with no magnetic disk mounted thereon. Therefore, the magnetic head on the upper carriage 15-5 can be prevented from colliding with the magnetic head on the lower carriage 15-4. However, there has been no measure against displacement of the disk holder 13 due to the effect of impact or vibration.